It is very often policemen or firemen on duty get injured or attacked at criminal scene or accident site. To ensure the safety of policemen and firemen on duty, and to accurately record the original criminal scene to avoid any future dispute, the US Police has adopted the in-car video system for policemen to record the process of law enforcement for use as evidence.
The currently commercially available wireless microphone for using with a police in-car video system includes a police wireless microphone, a wireless base station, and a video recording device or a digital video recorder (DVR) computer. The police wireless microphone is able to transmit digital data, such as audio signals, position coordinates or images from a remote location to the wireless base station. The data are further transmitted to a soundtrack of the DVR computer and recorded as a video file stored on an encrypted computer or database hard disk under protection.
According to the responses from policemen who have the experience in using the conventional police wireless microphone for many years, the conventional police wireless microphone has the following disadvantages:
(1) The policemen or the firemen on duty usually wear the wireless microphone on their waist or put in a pocket, so that they may conveniently use the wireless microphone in performing their task. However, the police wireless microphone is also frequently covered by the user's heavy coat or raincoat in the winter or on rainy days, or by the user's bulletproof vest, preventing the user from quickly turning on and operating various functions of the wireless microphone.
(2) When a policeman or a fireman enters into a building with complicated internal structure or moves to a location out of the wireless signal receiving range in performing his task, the wireless microphone worn by the policeman or the fireman might fail to receive wireless signals or could only receive discontinuous wireless signals. Under this condition, not all the contents of the communication between the wireless microphone and the base station may be completely recorded. While the conventional wireless microphone is equipped with the digital recorder function to record important evidences, the recorded evidences is subject to lose if the wireless microphone is damaged or lost in a criminal scene when the policeman fights with a gangster.
(3) Some of the police wireless microphones are equipped with the global positioning system (GPS) function, so that the position coordinates of the policeman wearing the wireless microphone and moved away from the police car may be continuously sent back to the base station. However, in the event the policeman wears or puts the wireless microphone at an unsuitable position, or when the wireless microphone is undesirably covered or shielded by, for example, the user's body, a building or a big tree, it is very possible the wireless microphone loses its GPS function. Under this condition, while the wireless microphone may still transmit data back to the base station, persons at the base station would not be able to locate the user's exact position without the help of the GPS. In some worse conditions, the policeman or the fireman getting injured in the site could not be timely rescued because the base station fails to locate his position.
(4) There are chances the policeman on duty is accidentally hit by a car or attacked by a scoundrel, and the policeman does not have enough time to use the wireless microphone to remotely turn on the in-car video system on the police car. As a result, no evidence is recorded.
(5) There are also chances the policeman driving the police car to chase a gangster and moving beyond the transmission distance of the wireless microphone is badly injured and becomes unconscious. Since the injured policeman has moved beyond the communication distance of the wireless microphone, the injured policeman may be not timely rescued because the supporting persons fail to locate his accurate position.